LTK001_09 Datasheet, PDF (1/8 Pages) Linear Technology – Thermocouple Cold Junction Compensator and Matched Amplifier

LTK001
Thermocouple Cold Junction
Compensator and
Matched Amplifier
FEATURES
■ _{0.75°C Initial Accuracy (A Version)}
■ _{Extremely Low Warmup Drift}
■ _{Preset Outputs for Type E, J, K, R, S, T}
■ _{Single 5V to ±20V Operation}
■ _{480µA Typical Supply Current}
■ _{Available in 8-Pin DIP Package}
U
APPLICATIO S
■ _{Thermocouple Cold Junction Compensation}
DESCRIPTIO
The LTK001 is a thermocouple amplifier supplied with a
matched cold junction compensator. By separating the
amplifier and compensator functions, the problem of
compensator temperature rise is virtually eliminated. The
compensator is a selected version of the LT^®1025 cold
junction compensator. The amplifier, which is also avail-
able separately as LTKA0x has been specially selected for
thermocouple applications. It has low supply current to
minimize warmup drift, very low offset voltage (<35µV),
high gain, and extremely low input bias currents (<600pA)
to allow high impedance input filters to be used without
degrading offset voltage or drift.
Matching of the kits is accomplished by separating the
compensators and amplifiers according to the polarity of
their initial (room temperature) errors. This eliminates the
need to sum the errors of the two components to find the
worst-case error.
The LTK001 has direct thermocouple outputs of
60.9µV/°C (E), 51.7µV/°C (J), 40.6µV/°C (K, T), and
5.95µV/°C (R, S). It also has a 10mV/°C output which can
be scaled to match any arbitrary thermocouple.
For multiple thermocouple applications using one com-
pensator, amplifiers may be ordered separately (LTKA0x),
still matched to the compensator.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. For typical performance curves and
applications circuits consult the LT1025 data sheet.
TYPICAL APPLICATIO
Type K 10mV/°C Thermometer
R2
R3**
100Ω
255k
FULL-SCALE TRIM 1%
V+
V_{IN K}
LT1025
GND R–V⁰
R1
1k
1%
–
+
*
C1
0.1µF
TYPE K
C2
0.1µF
V+
–
LTKA0x
+
V–
V_OUT
10mV/°C
R4*
V–
*R4 _≤
V ^– _{, R4 IS NOT REQUIRED (OPEN) FOR}
30µA
LT1025 TEMPERATURES ≥ 0°C.
**SELECTED FOR 0°C–100°C RANGE
LTK001 TA01
001fa
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